Hi everyone,

As a long-time user of Fiddler Classic, I’m writing to share an idea that could benefit both the community and the product's future. While Fiddler Everywhere is great and clearly the focus moving forward, there’s still a strong group of developers who prefer the speed, simplicity, and scripting power of Classic.

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⚠️ The Reality: Fiddler Classic Is No Longer Actively Maintained

Let’s be honest — Fiddler Classic isn’t just “a bit outdated.”
In recent documentation and forums, the message is clear:

“We recommend switching to Fiddler Everywhere for the latest protocol support.”

This effectively signals the end of active support for Classic. While that’s understandable from a product strategy point of view, it leaves a large number of users in a tough spot:

• Classic is still powerful and widely used, especially in Windows environments.

• But it lacks support for modern protocols like HTTP/2, TLS 1.3, QUIC, gRPC, Brotli, ZSTD, etc.

• Some users don’t want or need to move to a completely different interface — they just want Classic to stay viable.

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💡 The Proposal: Bring Premium Features to Classic via a Shared Subscription

Here’s what I propose:

Introduce an optional premium subscription tier for Fiddler Classic, shared with Fiddler Everywhere.

This would allow users to continue using Classic, while unlocking new features such as:

• ✅ HTTP/2, HTTP/3, and gRPC decoding

• ✅ TLS 1.3 and QUIC inspection

• ✅ ZSTD and Brotli decompression

• ✅ Modern cipher suite analysis

• ✅ Optional UI improvements like dark mode

And best of all:

If you're already a Fiddler Everywhere subscriber, you automatically get access to these premium features in Fiddler Classic — no double payment, no separate license.

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🎁 Why This Makes Sense

For Users:

• No forced migration — choose the tool that fits your workflow.

• Lightweight, scriptable Classic experience stays alive.

• One subscription, full flexibility.

For Progress (Telerik):

• Generates sustainable revenue to support modern protocol implementation.

• Maintains goodwill with loyal Classic users.

• Provides a “bridge” to Fiddler Everywhere for hesitant adopters.

• Keeps Classic usable without splitting the product line.

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🧠 Why This Is Technically Feasible

• Both Fiddler Classic and Fiddler Everywhere are built on the .NET stack.

• Protocol decoding, TLS inspection, and compression logic can be modularized or shared.

• A unified Telerik licensing system already exists — it can govern access to both products.

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💬 What Do You Think?

Would you support a shared subscription model like this?

Let’s not let Fiddler Classic fade away simply because it’s "not the focus" anymore. With a shared subscription model, both tools can thrive — and users can decide what works best for them.

If this idea resonates with enough of us, maybe we can bring it to the attention of the Fiddler team and show that there’s a real demand for keeping Classic alive — the modern way.

Thanks for reading!

When doing an IPR audit what is the actual License Type of Fiddler4 ? eg EULA, MIT Apache etc

https://www.telerik.com/purchase/license-agreement/fiddler-enterprise-support

https://www.telerik.com/download/fiddler

 

I am running into an issue where different business units of the company have finer grained security rules which prevent people from accepting / importing / trusting the OOTB Fiddler Root Certificate. Would it be possible for Fiddler to create a new CSR and import the new signed return certificate. This way I can sign the CSR with our internal CA which all hosts within the company have been configured to trust and accept.

Im using windows 7 32-bit both on my desktop and laptop both of them have fiddler 4.6 and both of them doesnt have winconfig. Its supposed to be on the upper left corner , but mines missing on two computer.any idea? can it be activated?

Not sure if this is a recent change, but I use Microsoft Outlook and Skype, and both are having connectivity issues when Fiddler is running. Also Windows 10 apps seem to be unable to have an internet connection as well.

The Spacebar keyboard shortcut only works if you're still focused inside of the session list. If you've clicked anywhere outside of the session list pane, pressing spacebar won't get passed to the session list.

For example, if you've clicked into the inspectors pane, spacebar will get sent to that pane, not the session list. To get back into the session pane (where spacebar would work), you have to either click back inside the session pane, which would change the session selection you were on, or employ some roundabout shift-tab trickery, like clicking the furthest left tab closest to the session list, then shift-tabbing a handful of times to get back into the session list. But this is pretty kludgy.

It'd be great if there was either a keyboard shortcut to switch focus back into the session list, or at least a tabbing shortcut multiplier which switches between panes, e.g., if Ctrl-Tab switches tabs, Ctrl-Alt-Tab switches between panes -- though this particular combo wouldn't work, as it's already claimed by Windows OS.

Hi,

I'm using the feature to right-click on requests and show or hide them heavily. It would be very nice to have this functionality from the QuickExec. Especially a ShowOnly by URL would be very nice. When using Fiddler for debugging the process ID may change frequently so that is not a good basis for filtering. On the other hand a modern development machine makes so many requests - if you have a few browser tabs open - that selecting hide for all is very inconvenient.

Hi guys. 

I investigate responses from . And Fiddler is tool for this.

But now I need  logs from Fiddler for 2-5 days and compare responses.

Fiddler grabs a lot of memory during 1 day and may cause my PC out of memory.

Request:

Automate autosaving saz files 4 hours with time-date in saz name, clear capture dialog and do it in the loop each next 4 hours.

 

Fiddler is a great tool & Composer an excellent feature of it.  I frequently have to reboot my dev. PC  for various reasons (actually it crashes a lot) and loosing my Composer URL history is a painful consequence.  Could the URL history be retained between invocations?  I use a set of about a dozen different endpoints frequentl, so a history size of 12-20 would likely be enough.

It would be even better if the last used request header and/or body and/or type (POST/GET/..) and/or Protocol (HTTP/1.1 etc.) for each URL could also be saved but perhaps that is asking too much.

 Bless you for making this tool. 

It would be great to have an option in the textWizard to convert an epoch date to a human-readable date.

Like: 1530417600 to "GMT: Tuesday 13 August 2019 08:32:48"

 

It would be great to have 2 options:

- convert epoch time to human readable time (GMT timezone)

- convert epoch time to human readable time (Local timezone)

 

Thanks for creating one of the most useful tools ever!

I recently reported a bug and I attached the wrong file. Fortunately it wasn't a sensitive file but I realized there is no way to edit my posts or attachments in this tracker. Ideally users should have the right to modify their own posts and attachments.

Add the functionality to check network status using FiddlerScript.

From www.redirect-checker.org/ and http://www.seoreviewtools.com/redirect-checker-tool/, I can see that e.g. https://www.lentillas.si/lentillas?tx=v is correctly 301ing to https://www.lentillassi.es/lentillas?tx=v. But fiddler does not report the 301, which made me think I screwed up my Apache directive.

The 301 IS reported for the non-https version.

I just upgraded Fiddler to v4.6.20171.26113, and noticed that the session count following a Find operation is no longer shown in the footer of the main window. It showed in my previous version of Fiddler.

Short of selecting "Edit->Remove->Unselected Sessions", and then counting what's left, is there another way? I often have several thousand sessions in my trace.

On a related note, Fiddler used to show the total number of sessions in the footer, as well. That was also very useful information.

I am a big fan of Fiddler, and use it on a daily basis. Thanks for the great product!

Even after closing the Fiddler application, the instance of the process is still running and when I try to start Fiddler a second time, it shows prompt telling Fiddler is already running and do you want to start fiddler any way.

If we choose Yes, then it will give another prompt telling port is in use and shall use random port.

This issue is coming only after upgrading the Fiddler to the latest version from the site 4.6.3. Older versions were fine.

Hello,
Good evening, let's get the idea straight.
The idea in order
I have a link and I want to do more than an automatic response.
As an example
Http://pro4social.com/ApiService.asmx (https://ssl.microsofttranslator.com/bv.aspx?from=&to=en&a=Http%3A%2F%2Fpro4social.com%2FApiService.asmx)

If this request:

"
<? xml version = "1.0" encoding = "utf-8"? > > soap: Envelope xmlns: soap = "http://schemas.xmlsoap.org/soap/envelope/" xmlns: xsi = "http://www.w3.org/2001/xmlschema-instance" xmlns: xsd = "http://www.w3.org/2001/XMLSchema" > < Soap: body < < Check4 xmlns = "http://pro4socialservice.org/" > <data> jxbhysqgmifgzqo/m78o3lci2gtgfxg = = </data> </check4> </soap: Body > </soap: Envelope > " (https://ssl.microsofttranslator.com/bv.aspx?from=&to=en&a=%3C%3F%20xml%20version%20%3D%20%221.0%22%20encoding%20%3D%20%22utf-8%22%3F%20%3E%20%3E%20soap%3A%20Envelope%20xmlns%3A%20soap%20%3D%20%22http%3A%2F%2Fschemas.xmlsoap.org%2Fsoap%2Fenvelope%2F%22%20xmlns%3A%20xsi%20%3D%20%22http%3A%2F%2Fwww.w3.org%2F2001%2Fxmlschema-instance%22%20xmlns%3A%20xsd%20%3D%20%22http%3A%2F%2Fwww.w3.org%2F2001%2FXMLSchema%22%20%3E%20%3C%20Soap%3A%20body%20%3C%20%3C%20Check4%20xmlns%20%3D%20%22http%3A%2F%2Fpro4socialservice.org%2F%22%20%3E%20%3Cdata%3E%20jxbhysqgmifgzqo%2Fm78o3lci2gtgfxg%20%3D%20%3D%20%3C%2Fdata%3E%20%3C%2Fcheck4%3E%20%3C%2Fsoap%3A%20Body%20%3E%20%3C%2Fsoap%3A%20Envelope%20%3E%20%22)

Then the Auto Responder reply this:

"
<? xml version = "1.0" encoding = "utf-8"? > > soap: Envelope xmlns: soap = "http://schemas.xmlsoap.org/soap/envelope/" xmlns: xsi = "http://www.w3.org/2001/xmlschema-instance" xmlns: xsd = "http://www.w3.org/2001/XMLSchema" > < Soap: body < < check4response xmlns = "http://pro4socialservice.org/" > <check4result> true </check4result> </check4response> </soap: Body > </soap: Envelope > " (https://ssl.microsofttranslator.com/bv.aspx?from=&to=en&a=%3C%3F%20xml%20version%20%3D%20%221.0%22%20encoding%20%3D%20%22utf-8%22%3F%20%3E%20%3E%20soap%3A%20Envelope%20xmlns%3A%20soap%20%3D%20%22http%3A%2F%2Fschemas.xmlsoap.org%2Fsoap%2Fenvelope%2F%22%20xmlns%3A%20xsi%20%3D%20%22http%3A%2F%2Fwww.w3.org%2F2001%2Fxmlschema-instance%22%20xmlns%3A%20xsd%20%3D%20%22http%3A%2F%2Fwww.w3.org%2F2001%2FXMLSchema%22%20%3E%20%3C%20Soap%3A%20body%20%3C%20%3C%20check4response%20xmlns%20%3D%20%22http%3A%2F%2Fpro4socialservice.org%2F%22%20%3E%20%3Ccheck4result%3E%20true%20%3C%2Fcheck4result%3E%20%3C%2Fcheck4response%3E%20%3C%2Fsoap%3A%20Body%20%3E%20%3C%2Fsoap%3A%20Envelope%20%3E%20%22)

The point is, I want more than auto Responeder.
As I mentioned upstairs, I only have one link.
And I do more than one request on the same link
I don't want to be a constant response.
It changes as the request matches.

# Too Short #
Remember, I only have one link.

If this request:
Serial"

Then Respone:
"1234567890"


&

If this request:
Active"

Then Respone:
Ok"

I apologize for prolonging the idea.
and
I'm sorry if there's anything wrong with my language.
Thank you, sir.

Could you please clarify if fiddler can be used in Windows terminal server without any license cost?

Fiddler users expect Fiddler to display URLs exactly as entered e.g. in the browser's address line.

However, when the URL contains an anchor (i.e. "http://...?...#anchor), this is not shown anywhere by fiddler, neither in column "URL" of the session list, nor in the inspector window.

I just want to know the simple way of getting Fiddler to pick up my router traffic.